Automatic primer for internal combustion engines



May 12, 1936. J. w. FITZ GERALD 2,040,253

AUTOMATIC PRIMER FOR INTERNAL COMBUSTION ENQINES Filed Marh 12, 1934 2Sheets-Sheet 1 L/Zvhn IKE/2575b May 12, 1936. 1.1. w. FITZ GERALD2,040,253

AUTOMATIC PRIMER FOR INTERNAL COMBUSTION ENGINES Filed March 12, 1934 2Sheets-Sheet 2 32 Z8- Z9 r V I7 1 I a 1 3O 4/ 38 5 I5 7/0 3 MIC 37 i 3536 Z0 22 I8 Ij i 4 o 4 w //G 1/ 5'0 28 3? I9 25 2/ m o Z0 F r L Z7/727 WE/gEPi/d 1%: 5* ea 35 6263922 X Q Patented May 12, 1936 UNITED STATESAUTOMATIC PRIMER FOR INTERNAL COMBUSTION ENGINES John w. Fitz Gerald,Milwaukee, will, assignor to Briggs & Stratton Corporation, Milwaukee,Wis., a corporation of Delaware Application March 12, 1934, Serial No.715,136

6 Claims. (01. 123-1875) This invention relates to new and usefulimprovements in automatic primers for internal combustion engines, andhas as an object to provide an automatic priming device which iscontrolled jointly by engine suction, and the thermal condition of theengine.

Another object of this invention is to provide a priming device of thecharacter described in which the admission of priming fuel to the englueis controlled by two independent-valves, one controlled jointly byengine suction and temperature variations, and the other controlledsolely by temperature changes.

A further object of this invention is to provide a priming device of thecharacter described,

defined by the appended claims, it being-understood that such changes inthe precise embodiment oi the hereindisclosed invention may be made ascome within the scope of the claims.

In the accompanying drawings, I have illustrated one complete example ofthe physical embodiment of my invention constructed according to thebest mode I have so far devised for the practical application of theprinciples thereof,

and in which: v

Figure 1 is an elevation view showing part of a carburetor and themanifolds of an internal combustion engine, and illustrating theapplication of this invention thereto;

Figure 2 is a side elevation view of the priming device per se;

Figure 3 is a'longitudinal section view through Figure 2 on the plane ofthe line 3-8;

Figure 4 is a section view taken through Figure 3 on the plane of theline 5-4; and- Figure 5 is a section view similar to Figure 3, butillustrating the valves in difierent positions.

Referring now more particularly to theaccompanying drawings in whichlike numerals indicate like parts throughout the several views, thenumeral 5 designates the carburetor of an internal combustion enginesupplied with fuel by asupply line 5 and conducting a combustiblemixture to an intake manifold! through a riser 8. As is customary, anexhaust manifold 9 is located in juxtaposition to the intake manifold.

The primer, indicated generally by the numeral ID, has an inlet llconnected to the supply line 8 by a pipe l2 and an outlet l3 connectedby a pipe I to the intake manifold to afford a direct communicationbetween the supply line and the manifold under certain conditions.

As best shown in Figures-3 and 4, the inlet ll leads to a transversebore K5 in the body l6 of the device with which two lateral bores I1 andt8 communicate. Intermediate the length of the body IS, the bores l1 and18 are counter- 10 bored as at l9 and, respectively, to define abruptshoulders forming valve seats 2| and 22, respectively.

Adjacent the valve seats, both bores I l and I8 communicate with a crossbore 23, the opposite ends of which are closed by plugs. At a medialpoint, the bore is connected with the outlet 13 through 'a bore 24.

The several bores formed in the body provide two separate fuel passagesfrom the inlet II to the outlet l3. These passages are independentlyclosed by needle valve members and 26 operating in the bores l9 and 20for cooperation with 'the valve seats 2! and 22, respectively.

The valve member 25 is controlled entirely 25 thermostatically. Itsouter end projects through a pocket 21 formed as a counterbore to thebore 7 l9, and has a stop flange 28 fixed thereto, be-

and its other end bifurcated to engage in an annular groove 32 in a head33 fixed to the extreme outer end of the stem of the valve member 25.

The disposition of the metals of the thermostatic member 30 is such thatwhen the ambient temperature is cold, the valve member is permittedto bemoved to open position by its spring 29, as shown in Figure 3, but asthe temperature rises, the thermostat 3B flexes and brings its free endin toward the body it to gradually close the valve member 25 against theaction of the spring 29.

The stem 31 of the other valve member 26' extends outwardly through abore 35, which forms a cylinder for a piston 36 secured to the stem. Theouter end of the stem 31 is slidable in a hole through a plug 38, whichcloses the end of the cylinder bore 35. Air bleeds 38' through the plug,permit the piston 36 to respondto suction created within the cylinderbore through its communication with the intake manifold I.

To insure such communication between the cylinder bore and the manifold,the inner end 39 of the valve stem is polygonal in cross section to atall times afford communication between the cylinder bore 35 and thecross bore 23, which, as hereinbefore noted, is in constantcommunication with the intake manifold.

The extreme outer end of the valve stem 31 has an annular groove 40 withwhich the bifurcated end of a second bi-metallic U-shaped strip 4|engages. The opposite end of the strip 6| is anchored to the body "5 bysecuring means 42.

The spring tension of the thermostatic strip 4| is sufiioiently light topermit engine suction acting upon the piston 36 to move the valve member26 to closed position just as soon as the engine becomes operative, butin the absence of main open to admit the maximum volume of auxiliary orpriming fuel to the intake manifold.-

Just as soon as the enginebecomes operative under its own power, thesuction builds up to a point suflicient to move the valve member toclosed position against the spring tension of the thermostat 4|, byitsaction upon the piston 36. The volume of priming fuel flowing to theintake manifold is thus materially reduced.

'I'hevalve member 25, however, does not close at this time, but remainsin open position until the temperature of the engine rises sufficientlyto flex the thermostatic strip 30 by reason of its proximity to theexhaust manifold, toward the body of the priming device sufiiciently' toovercome the spring 29 and move the valve member 25 to closed position.

While the valve member 25 is being moved to closed position by itsthermostatic strip 30, the thermostatic strip 4| is also being flexed bythe temperature rise to force its free end in toward the, body I6 01 thedevice so that if after the engine is operating properly and normaloperating temperature has been reached, and the effective suction of theengine is momentarily decreased as by suddenly opening the throttle, thevalve member 26 will not be moved, being held in closed position by itsthermostat 40.

. Obviously, when the engine cools off, after'being stopped, both valvemembers will again resume their open positions. I

From the foregoing description taken in connection with the accompanyingdrawings, it will be readily apparent to those skilled in :the art to.which this invention appertains, that this invention aii'ords a noveland extremely simple, fully automaticpriming device for internalcombustion engines and that an exceptionally fine and even control ofthe supply of primingfuel to the engine, is had at all times. A

What I claim as my invention is:

1. In combination with an internal combustion engine, an automaticpriming device comprising means providing a plurality of fuel passagesconnected in parallel forconducting fuel to the engine, valves in saidpassages for controlling the admission of fuel to the engine, enginesuction responsive means for closing one of said valves, thermostaticmeans for opposing said engine suction responsive means and operable tohold said valve open when the ambient temperature is low and in theabsence of engine suction and to hold the valve closed when the ambienttemperature is high even though engine suction ceases, a spring foryieldably opening the other valve, and thermostatic means opposing saidspring and tending to close said second designated valve as the ambienttemperature rises.

2. In combination with an internal combustion engine, an automaticpriming device comprising means providing a plurality of passagesconnested in parallel and adapted to'jointly supply fuel to the engine,valves in said passages for jointly controlling the admission of fuel tothe engine, engine suction responsive means for closing one of thevalves, temperature actuated means for opposing the suction responsivemeans and for holding said valve open until a predetermined degree ofengine suction has been reached, said temperature actuated means alsoholding said valve closed when a temperature of apredetermined highdegree has been reached regardless of variations in engine suction, anda second temperature actuated means for controlling the other valve. 1

3. In combination with an internal combustion engine, an automaticprimin'g device comprising a body having two fuel passages connected inparallel through which fuel may pass simultane-' ously for admission tothe engine, a valve for closing each passage, a piston connected withone valve and responsive to engine suction for closing the same, aspring for holding the other valve open, and temperature actuated meansfor controlling the actuation of said valves by the piston and spring inaccordance with the ambient temperature. 3

- 4. In combination with an internal combustion engine, an automaticpriming device comprising, a body having two fuel passages connected inparallel through which fuel may pass simultaneously'for admission to theengine, a valve to close each passage, 8. piston connected with onevalve and responsive .to engine suction for closing said valve, a springtending to hold the other valve open, and independent bi-metallicmembers anchored to said body and connected at their outer free endswith the valves for controlling the actuation of the valves by saidpiston and spring.

5. In combination with an internal combustion engine, anautomatic-priming device, comprising a body having two fuel passagesconnected-in parallel, a valve for closing each passage, a pistonresponsive to engine suction for closing one of said valves, springmeans for yieldably holding the other valve open, and bi-metallic U-shaped strips anchored to the body at one end 6. In combination with aninternal combustion 75 for opposing said engine suction operated meanswhereby said valve is regulated Jointly by engine suction and changes inthe ambient temperature, means for nulliiying any affect engine sectionmight have on the other valve, and thermostatic means responsive tochanges in the ambient temperature acting in conjunction with said lastnamed means for regulating said other valve.

Joan w. FITZ GERALD.

